The San Francisco Giants called up outfielder Jonah Cox on Friday and designated Ryan Borucki for assignment, bringing a 24-year-old speed threat to the majors as they reshuffle the roster. Cox was ticketed to be around and available for the finale at Coors Field, though there was no immediate word that he would start.

The move comes after Cox hit.400/.453/.644 at Double-A Richmond, a line built on 11 doubles, five triples and six homers, plus 27 stolen bases in 43 games. He also reached base in 40 of those 43 games, piled up 16 multi-hit efforts and struck out just 31 times against 16 walks, production that forced the issue even though he was not on the McCovey Chronicles community prospect rankings before the season. The Giants have had only 14 stolen bases all year, so Cox’s speed arrives as an obvious fit for a club that has not found that edge yet.

There was a hint of disbelief around the promotion. Brady Klopfer reacted in a work chat by saying, “I’m sorry WHAT,” a fair response to a player who was not considered a major prospect entering the season and had to remake his profile to get here. Cox, an A’s 2023 sixth-rounder, hit.257/.333/.398 in 597 plate appearances last season at Eugene, then made visible gains this year as his swing changes showed up in both the stat line and the underlying numbers.

Those numbers help explain why the call-up landed now. Cox posted a 1.130 OPS and a 196 wRC+ in Double-A, with a 16.9 percent strikeout rate and a 10.3 percent swinging strike rate, while also stealing 58 bases in 126 games a year ago. He followed Thursday’s 3-for-5 night with two infield singles, a stolen base and a double by earning a promotion the next day, turning a hot stretch into a shot at the next level.

Borucki’s exit closes the loop on a bullpen arm whose value had narrowed. He worked 23.2 innings with a 4.94 ERA, a 4.93 xFIP and minus-0.2 fWAR, and held left-handed hitters to a.195/.306/.244 line, useful numbers for a left-on-left reliever even as the three-batter rule and modern lineup construction squeeze that role. For Cox, the open question is not whether the Giants needed the speed, but how quickly they will trust it in a lineup that has been slow to run and suddenly has a runner who can change that with one swing, one read or one break from first.